White Paper: Mechanical & Fluid Systems
The Inside Story on Thermally Actuated Valves
SPONSORED BY: ![]()
As aerospace and defense platforms face tighter space and weight constraints, power limitations, and increasingly high operating temperatures, engineers are turning to passive temperature control solutions that reduce system complexity and failure points. Thermally actuated valves use temperature driven actuation to control flow within a system. Glenn Quinty, Senior Engineering Product Specialist at ThermOmegaTech, explains how thermal actuation works, why it excels in SWaP constrained systems, and where these solutions are deployed.
Don't have an account?
Overview
This article from Aerospace & Defense Technology features insights by Glenn Quinty, Senior Engineering Product Specialist at ThermOmegaTech, on the role and advantages of thermally actuated valves in aerospace and defense systems. These valves use a paraffin wax-filled phase-change thermal actuator that expands and contracts with temperature changes to mechanically open or close valve ports, enabling autonomous temperature-based flow control without external power, electronics, or controls. This passive actuation results in high reliability, repeatability, and simplicity—key benefits in demanding aerospace environments.
Thermally actuated valves excel in SWaP (Size, Weight, and Power) constrained systems by eliminating the need for wiring, sensors, and controllers, thereby reducing complexity and failure points. They provide smooth responses to temperature changes, avoiding pressure spikes common with electronic valves, which contributes to long service life, minimal maintenance, and dependable performance in harsh conditions. This makes them well suited for liquid cooling, thermal bypass, mixing, freeze protection, and fuel cell thermal management applications in platforms like fighter jets, drones, missile systems, radar, ground support equipment, auxiliary power units, and tactical vehicles.
These actuators generate force through paraffin wax expansion during phase change, producing consistent linear motion. Typical forces range from 25 to 150 pounds with strokes of 0.1 to 0.5 inches, while specially designed high-output paraffin actuators (HOPAs) can deliver over 1,000 pounds of force with strokes exceeding one inch for more demanding applications. Actuation set points range broadly from about 15°F to 300°F (-9.4°C to 149°C) with a defined temperature band of 10 to 20 degrees for accurate and repeatable control. Response times vary with temperature differential, usually between 5 to 10 seconds but potentially longer under smaller gradients.
Integration into existing aerospace and defense systems is straightforward, supported by customizable configurations of threads, materials, and set points. Lack of power or control requirements simplifies installation with minimal system modifications, making thermal valves suitable for both new designs and retrofits, meeting AS9100D aerospace certification standards.
In summary, thermally actuated valves offer a passive, reliable, and efficient method for autonomous temperature control, perfectly aligning with stringent aerospace and defense requirements for compact, robust, and low-maintenance thermal management solutions.